Use the eventsub revoke topic to montor and auto delete relevant EventSubs that user is/was using
A revoke also likely means they are no longer wanting to use your service, so you can unsubscribe anyway.
You can also then delivery an “are you sure” warning to the discord chanenl to nudge if the revoke was unexpected (password reset for example). Then jsut rebuild the subs/topics if they log in again.
(This is what I do on my own Discord/Twitch notification service, on revoke I kill that users evnetsub topics I have)
And if they don’t within 30 days then you GDPR wipe their data.
Create a uservoice
https://twitch.uservoice.com/forums/310213-developers
Citing your needs and use case